Disk drives for receiving removable disk cartridges, including conventional 3.5 inch floppy disk drives, must have some mechanism for detecting the insertion or presence of a disk cartridge in the drive. The actuator that carries the recording heads of the disk drive across the recording surfaces of the disk should not be allowed to move unless the presence of an appropriate disk cartridge which is non-drive damaging is detected. The removability feature requires that the disk drive have a cartridge insertion opening into which foreign objects can be inserted. If these objects physically engage the drive as a legitimate cartridge would, then the heads could be loaded onto or into the foreign object, thereby destroying the drive. Also, the spindle motor of the disk drive will be activated by a falsely detected foreign object, thereby generating particle debris. In the prior art, mechanical switches are typically employed to detect the presence of a disk cartridge within the drive. Such switches are typically positioned such that when a disk cartridge is inserted fully into the drive, the cartridge contacts the switch, thereby providing an indication that the disk cartridge is present.
"RETROREFLECTIVE MARKER FOR DATA STORAGE CARTRIDGE", U.S. Pat. No. 5,638,228, to Thomas, III, describes a retroreflective marker in which the reflection of a highly concentrated quasi circular lobe of light is captured by the aperture of a phototransistor in close proximity to a light emitting diode (LED). This emitter/detector pair is in the drive and the retroreflective marker is on the cartridge. The desired light lobe size is provided by the geometric size of the retroreflective elements within the retroreflective marker relative to the spacing of the emitter and the detector in the drive. The retroreflective marker reflects light in a retroreflective manner. The detector in the drive receives the light reflected from the marker, and the drive detects the presence of the cartridge responsive to the received light. This patent is incorporated herein by reference.
"LATENT ILLUMINANCE DISCRIMINATION MARKER SYSTEM FOR DATA STORAGE CARTRIDGES", Ser. No. 08/936,970, filed Sep. 26, 1997, to Thomas, III, et al., now U.S, Pat. No. 6,091,563 describes a latent illuminance marker, such as a phosphor tag, that is attached to a data storage cartridge. After being illuminated, the marker emits latent illuminance that is detected by a photodetector. The decay time or spectral characteristic of the emitted illuminance is measured and is used to identify the data storage cartridge. The latent illuminance marker emits and reflects light in a nondirectional or spherical manner. This patent is incorporated herein by reference.
The ability to discriminate between cartridge types, such as those containing a retroreflective marker and those containing a latent illuminance marker, after insertion into a data storage device but prior to putting the read/write heads on the recording media is of significant value and utility. Principally this utility comes from the ability to detect the difference between various capacities or generations of data storage cartridges in a downward media compatible data storage drive. This discrimination capability allows for drive/media specific adjustments to be made such as media rotation rate, data channel rates, location of Z track for initial seeking, or even mechanical adjustment in the drive like the active engagement of new crash stop locations. The ability of a disk drive to predetermine the type/generation of data storage cartridge inserted into it prior to enabling the spin-up and engagement of read/write elements also provides the drive system designer with new possibilities for cross-platform interchangeability.
A "caddy" cartridge provides cross drive platform compatibility, for example between mini-cartridges and personal computer cartridges. The ability to recognize the installation of a "caddy" into the drive prior to spinning up of the "caddy" and loading of heads is necessary. Rotational speed adjustments, Z track location information, data channel rate, and crash stop/ID and OD data track location information must be determined prior to read/write head loading. This invention provides a solution of these problems also.
Although the art of data storage cartridges and disk drives is well developed, there remain some problems inherent in this technology, particularly distinguishing between different types or generations of cartridges. Therefore, a need exists for a system that produces reliable detection and discrimination between data storage cartridges.